On Dec. 7, 1971, two patents issued to one of the coinventors hereof, Leo Esaki, such patents being U.S. Pat. Nos. 3,626,257 and 3,626,328 entitled "Semiconductor Device with Superlattice Region" and "Semiconductor Bulk Oscillator", respectively, both of which are incorporated herein by reference. These patents teach how to produce semiconductor devices with superlattice regions, the electrical properties thereof, and point out the prior state of the art with respect to theoretical considerations involving wave propagation in periodic structures, and the bulk negative resistance devices resulting therefrom.
Light emitting semiconductor devices as well as semiconductor laser amplifiers and oscillators are well known. These devices employ the allowed conduction and valence band states which are characteristic of the materials themselves. For a discussion of semiconductor lasers, see the book entitled "The Laser" by Smith and Sorokin, McGraw-Hill Book Company, Copyright 1966, and particularly Chapter 7 thereof.